In digital video, the requirement for the storage of audio/video data is considerable. Hence, a hard disk is preferably used to store the recordings. A hard disk is an element which exhibits a very good storage quantity/price ratio. At present, the file operating systems which manage the memory space of hard disks have been developed for work stations, that is, they are dedicated to a pure computing application.
To store video, provisions are then made to allocate specific resources (fixed spaces) on the hard disk in the form of several independent blocks making it possible to store and/or to read out several audio/video data streams. Such an organization has drawbacks. Specifically, if one wishes to record several video data streams simultaneously, one must do so in distinct independent blocks, thus making it necessary to perform to and from displacements between the independent blocks. These to and from displacements are manifested as frequent displacements of the reading/recording head of the disk.
Also, during these displacements, no activity is possible on the disk. This reduces the possible bit rate of recording, and reduces the performance of the disk since the bandwidth decreases. The same problem arises when one wishes to simultaneously record and read video data streams in and on the basis of independent blocks.